1. Field of the Invention
The present invention relates to a slide fastener slider having a pressing face for guiding linear elements while pressing inverted portions of the linear elements.
2. Description of the Related Art
Conventionally, in clothes, bags and the like, slide fasteners have been used to connect composition members such that the members can be opened or closed freely. A slide fastener is constituted of linear elements to be connected when they engage each other, strips of fastener tapes on which the linear elements are mounted in a longitudinal direction, and a slider which slides with the pair of fastener tapes sandwiched in a vertical direction.
The slider is constructed of a slider body in which an upper blade and a lower blade are connected and fixed integrally with a connecting post, and a pull tag. The upper blade comprises an upper plate and a pull tag attaching portion erected on the upper portion of the upper plate. The pull tag attaching portion has a space for attaching the pull tag. The lower blade is constituted of a lower plate.
In the internal structure of some sliders, a pressing face for guiding linear elements while pressing inverted portions of the linear elements is formed on the inner side face of a pair of flanges erected along right and left sides of a lower plate. The pressing face is formed into a step-like shape or a slope shape along a longitudinal direction of each flange, and the pressing face is constructed as a guide on which the inverted portions of the linear elements are mounted.
In general, the linear element is so constructed that with a pair of leg portions parallel to and extending from each coupling head, the end portion of each leg portion is connected to the end portion of a leg portion extending from each adjacent coupling head through an inverted portion. With this configuration, the linear element is constructed into a shape which is bent continuously in a coil-like shape. The inverted portion used in the present invention refers to a portion of the linear element which connects adjacent leg portions on an opposite side to the coupling head, as described above.
There has been proposed a slider in which a pressing face is formed in a step-like shape on a rear mouth side of a flange while it is formed in a slope shape from the step-like portion up to an end portion on a shoulder mouth 50 side of the flange (see Japanese Patent Publication No. 3618288).
A low blade of the slider described in Japanese Patent Publication No. 3618288 is configured such that, as shown in FIG. 7, a pair of flanges 41, 41 are erected along the right and left sides of a lower plate 40 and an elevated portion 44 is formed in the center of the top face of the lower plate 40 from a connecting post 42 to a rear mouth 43. Element guide passages 45 for linear fastener elements (not shown) are provided concavely between the elevated portion 44 and each of the flanges 41, 41.
The pressing faces 46, 46 are provided along the longitudinal direction of the inner side faces of the pair of flanges 41, 41. The pressing face 46, 46 is formed as a stepped portion having a vertically right-angle wall face 47, 47 provided downwardly to the lower plate 40 on the rear mouth 43 side, and formed as a slope face 48, 48 having a downward slope in the direction of the shoulder mouth 50 from the stepped portion. The slope face 48, 48 is expanded gradually from a bent portion 49 of the flange 41, 41 to the shoulder mouth 50 side.
Japanese Utility Model Publication No. 63-5533 has proposed another configuration of a slider in which a pressing face for guiding linear fastener elements while pressing inverted portions of the linear fastener elements. In the configuration of the slider, an intermediate step face is formed projectingly in a horizontal direction continuously from an end portion on a shoulder mouth side of each flange toward the shoulder mouth while the height of the top face of the intermediate step face is formed shorter than the height of the pressing face.
A lower blade of the slider described in Japanese Utility Model Publication No. 63-5533 is configured such that, as shown in FIG. 8, a pair of flanges 61, 61 are erected along the right and left sides of a lower plate 60 and an elevated portion 64 elevated from a connecting post 62 toward a rear mouth 63 is formed in the center of the top face of the lower plate 60.
Pressing faces 65, 65 are provided along a longitudinal direction of the inner side faces of the flanges 61, 61, respectively. The pressing faces 65, 65 are formed in an upward slope from a shoulder mouth 68 side to the rear mouth 63.
Intermediate step faces 66, 66 formed continuously from an end portion of the shoulder mouth 68 side of the flanges 61, 61 are provided projectingly in a horizontal direction toward the shoulder mouth. The height of the top faces thereof are formed smaller than that of the pressing faces 65, 65. The top faces of the intermediate step faces 66, 66 and the top face of the elevated portion 64 are constructed in a substantially the same height from the top face of the lower plate 60. Consequently, the elements can be stride over between the intermediate step face 66 and the elevated portion 64, so that a leg portion between an inverted portion and a coupling head of an element (not shown) is placed in a substantially horizontal state.
An element guide passage 67 is provided concavely between the elevated portion 64 and the intermediate step faces 66, 66, respectively.
In a slide fastener comprising linear elements for use in bags etc., a pull tag is often pulled upward or a slider is pulled upward when the slide fastener is opened or closed by sliding the slider. For this reason, the fastener tape is likely to be inclined so largely that it makes contact with a lower plate near an end edge portion on the shoulder mouth side of a flange of the slider. When the fastener tape is inclined so largely that it makes contact with the lower plate near the end edge portion on the shoulder mouth side of the flange, the fastener tape between elements and the end edge portion on the shoulder mouth side of the flange make a firm contact with each other.
If the slider continues to be slid in this firm contact state, a friction occurs between the bottom face of the fastener tape and the end edge portion on the shoulder mouth side of the flange, so that sometimes a thread in the fastener tape is broken.
In the conventional slider as described in Japanese Patent Publication No. 3618288, a downward slope 48 is formed such that it expands gradually from the height of a substantially intermediate position in the height direction of the flange 41 to the lower plate 40, the slope 48 extending from the bent portion 49 on the inner side face of each flange 41 to an end edge portion on the shoulder mouth side.
In a slider having such a structure, even when a lateral pulling force is applied to linear elements (not shown) to cause individual elements to be inclined, the inverted portions of the elements slide on the slope 48 and are pushed up, so that the inverted portions are guided up to the pressing face 46 in a pushed-up state. Consequently, the inclination of the fastener tape near the end edge portion on the shoulder mouth side of the flange 41 is controlled to be smooth forcibly.
When the inverted portions of the elements are sequentially carried onto the pressing face 46 on the rear mouth 43 side of each flange 41 in this state, the fastener tape is kept in a substantially horizontal state. As a consequence, the fastener tape (not shown) can be moved relative to the slider without making sliding contact with the top face of each flange 41 and a top plate (not shown) between the top plate and the lower plate 40. This makes it possible to prevent sliding contact between the fastener tape and the top face of the flange 41.
When a lateral pulling force is applied to an element at a position in an interval from the bent portion 49 of the flange 41 to the end edge portion on the shoulder mouth side before the inverted portion of the element rides on the pressing face 46, the inverted portion of the element rolls on the slope, so that the fastener tape between the elements does not turn to a horizontal state but is inclined. Particularly, the interval between the end edge portion of the flange 41 on the shoulder mouth 50 side and the end edge portion on the rear mouth 43 side of the connecting post 42 in the back-forth direction of the slider is formed wide. For this reason, when the lateral pulling force is applied to the element at any position between the bent portion 49 of the flange 41 and the shoulder mouth side end edge portion, the leg portion of the element is inclined easily, so that the fastener tape does not turn to the horizontal state but is inclined.
When the leg portion of the element is inclined, the height position of the fastener tape in a region between the bent portion 49 of the flange 41 and the shoulder mouth side end edge portion becomes lower than the top face of each flange 41. Thus, although the fastener tape is raised relative to the top face of the flange 41 across the bent portion 49 of each flange 41 on the rear mouth side, it is lower than the top face of each flange on the shoulder mouth 50 side.
Consequently, the fastener tape turns to a state directed obliquely upward toward the shoulder mouth 50 side across the bent portion 49 of each flange 41. On the other hand, the bottom face of the fastener tape is inclined relative to the end edge portion on the shoulder mouth side of each flange, so that the bottom face of the fastener tape makes contact with the end edge portion on the shoulder mouth side of the flange as if it is pulled up from the bottom. If the slider is still slid in this state, the breaking of threads occurs in the fastener tape due to friction by sliding contact with the end edge portion on the shoulder mouth side of the flange.
In the slider as disclosed in Japanese Utility Model Publication No. 63-5533, the intermediate step face 66 continuous from the shoulder mouth side end portion of each flange 61 is provided projectingly in the horizontal direction toward the shoulder mouth 68.
The provision of this intermediate step face 66 gives the following advantage. That is, even when the lateral pulling force is applied to the element nearer the shoulder mouth 68 side than the end edge portion on the shoulder mouth side of each flange 61, the leg portion of the element can be supported by the elevated portion 64 formed in the center of the top face of the lower plate 60 and the intermediate step face 66. Consequently, the leg portion between the inverted portion and the coupling head of the element can be prevented from being inclined without turning to the horizontal state, thereby preventing the fastener tape portion between the elements from being inclined.
Moreover, the fastener tape and the slider can be moved relative to each other while preventing the fastener tape portion between the elements from being inclined. With this configuration, as the height position of the fastener tape, it can be maintained at a position between the top plate (not shown) and the top face of the flange 61, thereby preventing the fastener tape from making contact with the top face of the flange 61 and the shoulder mouth side end edge portion.
When the lateral pulling force is applied to the element supported in a substantially horizontal state between the elevated portion 64 and the intermediate step face 66, the leg portion of the element can be supported in the substantially horizontal state not so as to be inclined by the elevated portion 64 and the intermediate step face 66. However, when the leg portion of the element goes out of the support by the elevated portion 64 and the intermediate step face 66, and the leg portion is inclined, the inclined leg portion of the element cannot be returned to the substantially horizontal state.
When the fastener tape enters the slider body in a state in which the leg portion between the inverted portion and the coupling head of the element is kept inclined without turning to the substantially horizontal state, the height position of the fastener tape becomes lower than the top face of each flange.
Accordingly, the bottom face of the fastener tape makes contact with the shoulder mouth side end edge portion of each flange. If the slider is slid in this state, a frictional force occurs by sliding contact between the shoulder mouth side end edge portion and the fastener tape, so that breaking of threads is brought about in the fastener tape due to friction.